1. Field of the Invention
This invention relates to a method of removing impurities or contaminants; such as, arsenic or selenium; from hydrocarbonaceous fluids, such as synthetic crude oil or fractions thereof.
2. Description of the Prior Art
There has been a resurgence of interest in sources of energy that were formerly considered not to be competitive. These sources of energy include shale oil, liquefied and/or gasified coal, the bitumen from tar sands, and the like. Frequently, these fluids are combined under generic terms like "synthetic hydrocarbonaceous fluids", "synthetic crude oil", or "synthetic oil fractions". Some of these synthetic hydrocarbonaceous fluids contain contaminants that could reduce the activity of certain catalysts that are used in hydrogenation and other processes to which such hydrocarbonaceous fluids may be subjected before used as sources of energy. Even if such hydrocarbonaceous fluids are employed directly as fuels, the removal of such contaminants may be desirable for environmental purposes. Consequently, it could sometimes be preferable that the contaminants be removed, or lowered in concentration.
The prior art includes methods of removing arsenic from hydrocarbon charge stocks, such as described in U.S. Pat. No. 2,778,779. Such methods have included using iron, nickel and cobalt oxides to remove arsenic from streams of naturally occurring crude oil fractions; for example, naphtha or straight run gasoline. In that process, the oxides were employed at a low temperature, such as from room temperature to about 200.degree. F, without regard to the atmosphere under which the reaction takes place and with substantial amounts of water, the oxide acting as an oxidizing agent and oxidizing the arsenic to a water soluble arsenic oxide. In this way, the arsenic oxide is dissolved in the water and removed from the naturally occurring crude oil or oil fraction.
Also, as disclosed in U.S. Pat. No. 2,781,297, arsenic has been removed from similarly naturally occurring crude oils by contacting them with a metallic salt of a strong acid at low temperature, such as room temperature, without regard to the atmosphere under which the contacting takes place. In this particular process, it was taught that oxides do not work for removing arsenic.
One of the most pertinent patents of which we are aware is U.S. Pat. No. 3,496,099, which describes the catalytic hydrogenation of hydrocarbons to effect the precipitation of an insoluble iron salt of the iron porphyrin within a hydrogenating catalyst that increases in concentration longitudinally and concurrently with the flow of the feed; the feed being naturally occurring hydrocarbons.